Magnetizable wedge for dynamo-electric machines.



J. M. BARR. l x MAGNBTIZABLE WEDGB POB. DYNAMO LEGTRIG MACHINES. APPLCATION FILED AUG. 1969.

984,182. Ptennea Feb.14.,1 911.A

MII l" wmv assis INVENTlm..

Y i i ATTORNEY UNTED 'STATES PATENT OFFICE.

JOHN M. BARR, OF WILKNSBURG, PENNSYLVANIA, ASIGNOR TO WESTINGHOUSE ELECTRIC AND MANUFACTURING'COMPANY, A CORPORATION OF PENNSYLVANIA.

MAGNETIZBLE WEDGE 'FOR DYNAMO-ELECTRIC MACHINES.

Specification of Letters Patent;

Patented Feb. 14,1911.l

Application ined August 2, 1909. serial No. 510,857.

To all whom 'it may concern:

V-Be it known that I, JOHN M. BARR, a citi-- zen of the United States, and a resident of lVilkinsbnrg, in the Acounty of Allegheny and State of Pennsylvania, have invented a nen1 and' useful Improvement in MagnetizableW'edges for Dynamo-Electric lfaclliines, o which the following is a specification. My invention relates to electrical apparzb tus, and it has special reference to magnetiz`l able core members which are provided with coil-containing slots,

The object of my invention-is toprovide a simple and durable means for eilectually holding the coils of open-slot machines in position against the action of centrifugal,

y magnetic and other forces which tend to displace them, and 'at the same time to, provide the operating advantages which pertainto machines having partially closed slots.

Considerable diiiculty has 'been 'experil` enced in attempting to use magnetizable `wedges for holding-the coils of open-slot machines in position by reason of the fact -that it is necessaryto electrically vinsulate the wedges from the core teeth in order to prevent excessive losses in the machine. For mechanical and magnetic reasons, the insulation must be very thin in order to permit the. metal wedge to be securely held in posi# tion by the small grooves which are usually provided 'in the teeth ofopen-slot machines and in order to minimize the magnetic reluctance. Under these conditions, thin insulating strips are almost sure to be destroyed or mutilated when the wedges are driven into position 'if the fit is sufiiciently close to prevent displacement in operation.`

According to 'my present inventioml provide .a sheet metal wedge which is prefer- 'a-bly bent into the form-of a flattened tube having oneside cut away, and its size is such that it can readily be slipped into the grooves of a core slot after thin insulating strips have been introduced, a strip or rod of brass or other non-magnetizable material being finally forced into the tubular member to spread it and press it into very close engagement with the grooves without necessarily producing any downward pressure on the coils within the slot.

Figure 1 of the accompanying drawingsisfa partially sectional elevation of ya 'dy nemo-electric machine embodying my ,in-

structures embodying my invention.

- Referring to the drawings, the structure here shown. comprises a magnetizable core member lv having a plurality of slots 2, in

-ivliieh coils 3 are located, and end plates 4 between which the core lamime are assenti-` bled. Each of the slots 2 has substantially parallel side walls which are provided with grooves 5 that extend longitudinally oi the slot near its open side. After the coils 3 are placed in the slots, they are held rigidly in position-by "means of wedges 6 which are so constructed as toimprove the characteristics of themachine with which they aref-employed as well as to prevent the displacement of the coils.

I have shown three forms of wedges which are illustrated b v transverse sectional views in Figs. 3i, 4: and 5. Referring particularly to the .wedge shown in Fig. 3, 'a magnetizable strip 7, preferably formed of sheet iron, is provided with lateral projections which are of hook shape in cross section and form a hollow -bar open 'at one side. The form of theiprojections and the size of the strip are such thatthe hol-low bar fits loosely intoA the grooves 5 provided in -the walls of the slot and closes the sides'of the slot after the 'coils are in position. Since the bar 7 is formed of sheet iron, it is, to a greater or less degree, resilient, and it is preferably arranged to fit loosely into the groove 5 in order that thin strips 8 of insulating Inateria-l may be used for electrically separating the bar from the laminated ironl of the core. After the insulating strips and.' the hollow bar arci-n position, a wedge ll of' non-magnetizable material is driven-into the bar, in order to expand it into the grooves 5,

making a particularly rigid Wedge structure that'is capable of holding the coils firmly in position Without being dependent upon the outward pressure o the coils for preventing its`displacement.

Reference may now'be had to the modified structure shown in Fig. 4 o the drawings, in which like parts are designated by the same referencecharacters. The bar 7 here shown 'is provided with lateral projections 10 which are bent down and are l ladapted to enter` the groove 5, the non-mag netizable wedge 9 lacing, in this case, also adapted to fitinto the groove 5 and to force the projections l() outwardly .nd upwardly against the upper half of the side of the groove. The projections l should be insulated from the. core member by means of insulating stripe 8, as in the form shown in Fig. 2. In each instance, the magnetizable bars are preferably provided with longitudinal slots 11 in order to prevent excessive iron losses and in order to approximate more nearly the forni and operating char acteristics of partially closed slots.

In Fig. 5, the slots ll are extended throughoutthe entire length of the hollow inagnetizable bar so that two channel-shaped members 1Q are provided in lieu of the parts T of the other figures. The mclrllocls 12 are lo he regarded as parts of a single bar, since they cooperate with the wedge and the core Vslot grooves to perform the same functions as are performed b v the parts shown ln Figs.

and 4. The forni of' device -sh'own in Fig.

is'particnlarly well adapted for'machines having relatively large core slots.

Variations in size and arrangement of parts may be effected Within the Yspirit and scope of my invention, and I desire that only such limitations shall be imposed as are indicated in the appended claims.

I claimA as my invention:

1. A coil -rciaining wedge for open -slot dynamo-electric machines comprising a yieldinej magnciizablc bar having lateral projeclmns of: hook shape in transverse seotion and a non-magnetizable wedge which is adapted to be forced into the magnetizalile bar to expand it after it is placed in position.

2. A coilretaining Wedge for open-slot dynanv:-elr-rtric machines comprising .a

yielding niagnetizable bar havinglateral projections that are bent to form achannel and .a non-magnetiza-ble strip or Wedge ing a plurality of coro slots in its peripheryand grooves in the. side walls of the slots near their open ends2 coil-retaining WedgeS comprising yielding sheet iron hars placed in the months of the slots and loosely engaging the grooves and nonmagnetizuble wedges for expanding the niagnetizable bars into firm engagement with the grooves.

5. The combination with a cylindrical. core member of a dynamo-electric machine having a plurality of core. slots in its periphery and grooves in the side walls of the slot-s near their open sides, of coil-retaining meinbers eomprisin0r yielding sheet iron hars of channel shape ocatcd in the mouths of the slotsand engaging the grooves, and nonmagnetizable wedges adapted io oe forcibly inserted in the magnetizable hars to expand the same into rigid engagement. with the In testimony whereof: l. hai-e hereunto subscribed my name this' 29th day of July, 

